Variable capacity mechanism for fluid pumps and motors



July 22, 1969 o. E. RosAEN 3,456,593

VARIABLE CAPACITY MECHANISM FOR FLUID PUMPS AND MOTORS Filed June 25,1967 4 Sheets-Sheet l July 22, 1969 o. E. RosAEN 3,456,593

VARIABLE CAPACITY MECHANISM FOR FLUID PUMPS AND MOTORS Filed June 26,1967 4 Sheets-Sheet 2 July 22, 1969 o. E. RosAEN i 3,456,593

VARIABLE GAACITY MECHANISM FOR FLUID PUMPS AND MOTORS Filed June 26,1967 4 Sheets-Sheet i'.

BIZ

Zl 284 y INVHNTOR.

OSCA R E. ROSA EN ATTORNEYS July 22 1959 o. E. ROSAEN 3,456,593

VARIABLE CAPACITY MECHANISM FOR FLUID PUMPSv AND MOTORS Filed June 26,1967 4 Sheets-Sheet 4 INVENTOR.

FIG- Il OSCAR EROSAEN BY #www www ATTO RN US United States Patent OVARIABLE CAPACITY MECHANISM FOR FLUID PUMPS AND MOTORS Oscar E. Rosaen,Grosse Pointe Shores, Mich. (1776 E. Nine Mile Road, Hazel Park, Mich.48030) Filed June 26, 1967, Ser. No. 648,681

Int. Cl. F04c 15/04, 3/00 U.S. Cl. 103--120 12 Claims ABSTRACT OF THEDISCLOSURE A variable capacity mechanism for expansible chamber fluidpumps and motors of the rotary vane type in which the cam means whichguide the vanes for extension and retraction in the pumping chamber isdivided into two members having substantially semi-circular surfaces,one members being fixed with its cam surface at a substantially constantradius from the rotor, and the other member having a similar cam surfaceradius and being movable with respect to the rotor, the ends of the cammembers having sliding tongue and groove engagement and shaped to besubstantially tangent to arcs concentric with the cam for smoothtransition of the vanes from the iixed to the movable member andvice-versa, and the movable member being cam actuated responsively topump delivery or motor working pressure toward and away from said rotor,with means for pressure balancing the rotor, the movable cam member, andthe individual vanes, with the cam surface contours and thepressure-balancing being such as will provide a smooth surge-freetransitionas the vanes move between pressure and suction areas of thepump or motor chamber.

BACKGROUND OF THE INVENTION Field of the invention The invention relatesto expansible chamber, variable capacity, rotary vane pumps and motors,the pumps having delivery pressure responsive means adjustable toposition the vane-guiding cam for maintaining or varying pump deliveryvolume according to downstream requirement with predeterminedsubstantially constant pressure, and the motors having similarlyfunctioning means for load-compensation depending upon variable workingpressure.

Description of the prior art Patents which indicate means for varyingthe capacity of a pump or motor of this general type by adjusting aportion of the vane-guiding cam member are the following: U.S. PatentNos. 1,697,041; 2,031,749; 2,170,786; 2,222,144; 2,458,023; 1,693,540;Swiss Patent No. 101,021; German Patent Nos. 415,472 and 606,178; andBelgian Patent No. 502,418. Additionally, applioants issued Patent No.3,272,139 shows a specialized type of variable capacity pump in which amovable cam portion is connected with a fixed cam portion by means ofhinged ramp elements, and is adjusted responsively to pump deliverypressure. Problems relating to the above patents include not merely thecomplexity of construction, but the difficulty in obtaining movable camadjustment, relatively slower response times, the effects ofsurge-producing transitional pressures, and presence of other unbalancedforces which will adversely aifect the operation of the pump or motor,all of which are corrected by the present variable capacity mechanism.

SUMMARY OF THE INVENTION In the present pump or motor, the fixed andmovable cam ring members have cam surfaces disposed on a radius which islarger than the rotor radius, with the movable cam member adjustablebetween a position where its `radius is substantially concentric to andspaced from the rotor to a position at which the mid-section of themovable cam member is closely adjacent to the rotor, so that fluid movesfrom the inlet disposed on one side of said mid-section around to theoutlet disposed on the other side of said mid-section, with the inletand outlet respectively connected to diametrically opposite portions ofthe pump or motor chamber to substantially balance the rotor againstunequal forces, and with the individual vanes substantially balanced atall times as they move between differing pressure areas of the chamber.In the case of a pump, there are special restricted orifice pressureports to the inner ends of the vanes when in transition periods, theorices admitting pressure proportionately as the same pressure ispermitted to escape through passages formed between the vane slots andbeveled edges of the vanes on the leading sides thereof. Adjustment ofthe movable cam member is accomplished through the means of a slidingcam actuator moved in response to pump delivery or motor workingpressure as opposed by a spring or the like. Means are provided forbalancing the movable cam member against unequal pressure forces actingthereon, so that it can be readily adjusted by the aforesaid actuator.The midsection of the movable cam member, in the chamber areaintermediate the inlet and outlet, is contoured such that when it isadjusted to an optimum or normal operational position, the cam arc issubstantially concentric with the rotor periphery, producing improvedsurge-free operation.

DESCRIPTION OF THE DRAWINGS A more complete understanding of theinvention may be had by reference to the accompanying drawingsillustrating a preferred embodiment of the invention in which likereference characters refer to like parts throughout the several views,and in which:

FIG. 1 is a longitudinal cross-sectional View through a pump of the typedescribed embodying the present invention;

FIG. 2 is a lateral cross-sectional View of the pump taken substantiallyon the line 2-2 of FIG. 1;

FIG. 3 is a fragmentary lateral cross-sectional view taken substantiallyon the line 3 3 of FIG, l:

FIG. 4 is a perspective view of the cam members of the pump;

FIG. 5 is a perspective view of a preferred vane element for use in thepresent pump;

FIG. 6 is a lateral cross-sectional view of a fluid motor of the typedescribed embodying the present invention;

FIG. 7 is a longitudinal cross-sectional View of the motor takensubstantially on the line 7-7 of FIG. 6;

FIG. 8 is a cross-sectional view taken substantially on the line 8-8 ofFIG. 6 but showing only the motor end Cap;

FIG. 9 is a perspective view of the cam members of the motor;

FIG. 10 is a perspective view of a vane element used in the motor ofFIGS. 1-9; and

FIG. 11 is an enlarged fragmentary view of the rotor and cam used in thepresent invention to show contour details.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1-5 illustrate thepresent invention as embodied in a pump comprising a housing structure10 having a pumping chamber 12 closed -by an end cap structure 14. Arotor 16 is carried in the pumping chamber 12 and splined to a shaft 17supported by bearings 18 and 20 respectively carried in coaxial bores 22and 24 provided through the housing 10 and end cap structure 14. The

open end of the bore 24 in the end cap 14 is closed by` a plate 26secured thereto by any means such as screws 28.

The periphery of the rotor 16 has a plurality of angularly spacedtransverse slots 30` as shown in FIG. 2 in which are radially slidablycarried a plurality of vane elements 32, with the inner ends of thevanes 32 being subjected to fluid pressures introduced into transversebores 34 provided at the inner ends of the slots 30. A vane 32 is shownin FIG. to have an outer beveled end 36 and beveled edges 38 on theleading side thereof (i.e. facing the direction in which the vanes aremoving as the rotor rotates as indicated by the directional arrow inFIG. 2).

A iixed cam member 40 is secured in the pumping chamber 12 and encirclesapproximately one-half of the rotor 16. The cam member 40 has an innercam surface 42 which is concentric with the rotor outer periphery andradially outwardly spaced therefrom. A movable cam member 44 is disposedin the pumping chamber 12 and has a portion 46 extending oppositelyyfrom the ixed cam member 40 and supported for sliding movement in ahnaperture 48 in the housing structure 10. The movable cam member 44 hasan inner cam surface 50 formed on a radius substantially similar to theiixed cam member inner surface 42, except for a media portion to bedescribed, and is adapted for adjustment toward and away from the rotor16 to move the medial portion of the inner cam surface 50 between a zeroor minimum expansion position (shown in FIG. 2), wherein the cam surface50 is substantially concentric to and spaced from the periphery of therotor 16 and fluid delivery is zero or minimum, to a maximum deliveryposition, indicated in FIG. 11, where the medial portion of the innercam surface 50 is closely adjacent the rotor periphery, the cam surface50 thereby forming adjacent slopes relative to the rotor periphery toprovide adjacent contracting and expanding volumes between successivevanes in the pumping chamber 12 and to guide the vanes 32 for retractionaiid extension into and out of the slots 30, fluid delivery being at amaximum.

The ends of the cam members 40 and 44 have slidable tongue and grooveengagement as seen in FIG. 4, and the ends of the cam surfaces 42 and 50are flattened as at 51 to be substantially tangent to arcs concentricwith the rotor 16, and parallel to the direction of cam member 44adjustment, so that the vanes 32 will ride smoothly from one cam surfaceto the other as the rotor rotates, regardless of the adjusted positionof the movable cam member 44.

The housing 10y and end cap 14 are arranged to provide an inlet recess52 adjacent that portion of the movable cam member 44 on one side of itsmedial portion, and an outlet recess 54 adjacent the other portion ofthe movable cam member 44 on the other side of its medial portion. Theinlet and outlet recesses 52 and 54 are connected through respectiveinlet and outlet ports 56 and 58 provided in the housing 10 with asource of fluid (not shown) and a tluid pressure user (not shown)respectively. Thus, when the movable cam member 44 has been adjustedtoward the rotor 16, uid will be drawn into the inlet recess 52, carriedaround the periphery of the rotor 16, to rotate same in acounterclockwise direction as seen in FIG. 2, and discharged through theoutlet recess 54, the delivery volume being a function of the proximityof the movable cam member 44 to the rotor 16.

The xed cam member 40 is provided with an outer peripheral groove 60extending `from the end adjacent and open to the inlet recess 52 to apoint 62 closely adjacent and closed off from the outlet recess 54. Agap 64 connects the groove 60 with the pumping chamber 12 at a locationadjacent the rotor 16 substantially diametrically opposite the portionof the rotor which is exposed to the inlet recess 52. Pump deliverypressure is introduced through a passage 66 connecting the outlet recess54 with an annular space 68 adjacent the shaft 17 of the rotor 16, theopposite sides thereof being openly communicated through bores 70`extending through the rotor 16, and the pressure is connected by meansof a passage 73 bored in the housing 10 radially outwardly to a smallside recess 72 in the iixed cam member 40, the recess 72 being open tothe pumping chamber 12 adjacent the rotor 16 at a locationsubstantiallyl diametrically opposite to the chamber portion adjacentthe outlet recess 54. Admission of inlet and outlet pressures to thesediametrically opposite portions of the rotor tend to balance the rotoragainst fluid pressure forces which would otherwise exert binding andWear-producing stresses on the rotor 16 and its shaft 17.

It will be seen that as the rotor 16 rotates, the outer ends of thevanes 32 will move between areas of different pressures. These pressuresneed to be balanced at the inner vane ends with substantially similarpressures to prevent the vanes from being 4forced against the camsurfaces 42/and 50 With'too great a force, or from being retracted intotheir slots which would eliminate pumping. Therefore, arcuate recesses74 and 76 respectively are provided in the housing 10` and cap 14adjacent the pumping chamber 12 along an arc registering with the bores34 at the inner ends of the vane slots 30, and in that area where theouter ends of the vanes 32 would be subjected directly to pump dischargepressure. The recesses 74 and 76 communicate with pump delivery pressureby means of the aforesaid passage 66 extending toward the hub of therotor 16. Substantially diametrically opposite, a second set of arcuaterecesses, namely recess 7'8 in the housing and a similar recess (notshown) in the end cap are provided adjacent the pumping chamber 12 on anarc registering with the bores 34 in that area where the outer ends ofthe vanes 32 are subjected to pressure from the recess 72 previouslydescribed. The recess 78 and the end cap recess (not shown) communicatewith delivery pressure from the passage 73 extending between annularspace 68 and the recess 72.

Other arcuate recesses 82 and 84 are provided respectively in thehousing 10 and cap 14 adjacent the pumping chamber 12 on an arcregistering with the bores 34 as the vanes move through the areadirectly adjacent the inlet recess 52. The recesses 82 and 84 areconnected by means of a passage 86 with the inlet recess 52.

The aforesaid recesses introduce inlet and outlet pressures to the innerends of the vanes 32 to provide proper end-to-end balancing thereof asthey move.

Passages 88, all substantially the same, extend outwardly from theannular space 68 at the hub of the rotor and are connected throughrestricted orifices 90 with the pumping chamber 12 on an arcuate lineregistering with the bores 34 at the inner ends of the vane slots 30. Arestricted pressure introduced at these points enables the vanes to movebetween areas of different pressure (that is, from an inlet pressurearea to an outlet pressure area or vice-versa) without any sudden jumpin balancing pressures which might tend to damage the vanes, causenoise, and produce undesirable surges of pressure. The orifice 90 at thelocation diametrically opposite the inlet recess 52 and designated bythe letter A in FIGS. 2 and 3 is required to hold the vanes outwardly inan area where they might otherwise tend to part from contact with thecam surface. Also, small grooves 92 are provided at the leading ends ofthe arcuate recesses 74 and 78, and at the orice 90 at location A. Thesegrooves 92 serve the purpose of augmenting a smooth, surge-freetransition from one balancing pressure to another. The vanes 32, asshown in FIG. 5, have the beveled edges 38 which are constructed toprovide communication between the inner and the outer ends of the vanes32 and are of a total cross-sectional area substantially equal to thecross-sectional area of each of the orifices 90. Thus, the pressureadmitted through the lorifices 90 will be permitted to escape withcontrolled ow.

The housing 10 has a side recess 94 closed by a cover plate 96 securedby any means such as screws 98. An

actuator member 100 is slidably supported in the recess 94 on a centraltube 102 extending from a fluid fitting 104 as shown in FIG. 2. The tube-2 is hollow for the admission -of pump delivery pressure which isconducted to the fitting 104 through a conduit (not shown) or the likeconnected with the outlet recess 54. Pressure admitted throguh the tubeto the interior of the actuator 100 tends to move the actuator in thedirection of the arrow in FIG. 2, and is opposed by a spring 106compressed between the inner end of the actuator 100 and the recess ofan adjustable fitting 108 which can be adjusted to vary spring'-compression and thus determine the pressure change required to move theactuator member 100.

The outer end surface 110 of the movable cam member portion 46 is slopedas shown in FIG. 2 at about a ten degree angle from the normal todirection of movement, and abuts a similarly sloped surface 112 of theactuator member 100, so that as the actuator member 100 is movedlaterally back and forth dependent on variations in pressure admitted toits interior, the movable cam member will be cammed toward or away fromthe rotor 16. Thus, when the downstream fluid demand of the pump isdecreased, for example by closing of a downstream valve, the deliverypressure will tend to increase, moving the actuator 100 against theforce of the spring 106, and the fluid pressure acting on the interiorvane-guiding cam surface 50 of the movable cam member 44 will cause themovable cam member to move away from the rotor 16 toward 4or to theposition shown in the drawings to thereby decrease fluid delivery fromthe pump. As the requirements for uid pressure are increased, such as byopening a downstream valve, the pressure within the actuator 100 willcorrespondingly decrease, and the spring 106 will move the actuator tothereby cam the movable cam member 44 radially toward the rotor 16, toincrease pump fluid delivery.

It will be seen that the movable cam member portion 46 is subjected onone side to the delivery pressure of the pump, and therefore a passage1'14 through the cam member portion 46 admits pressure fluid to a recess116 on the other side of the cam member portion 46 through a restrictedorice 118. The size of the recess 116 is such as will substantiallybalance the movable cam member portion 46 from side-to-side to prevent atendency toward binding thereof.

A spring-loaded vane member 120 is provided in a slot 121 on thepressure side of the movable cam member portion 46 to engage the side ofthe aperture 48 and minimize leakage of pressure therethrough. The innerend of the slot 121 is recessed for the spring and connected withdelivery pressure through a passage 122 extending between the pressurepassage 114 and the face of the movable cam member sloped surface 110.The pressure to this surface 110 tends to keep it and the actuatorsloped surface 112 from sticking, so that response to pressure movingthe actuator member 100 will be instantaneous. Fluid leakage into theside recess 94 will be returned to the inlet recess 52 through a passage124 in a slide plate 126 secured to the side of the aperture 48 as seenin FIG. 2.

FIGS. 6-l0 illustrate the present invention as embodied in a loadcompensating, expansible chamber uid motor comprising a housingstructure 210 having a working chamber 212 closed by an end capstructure 214. A rotor 216 is carried in the working chamber 212 andkeyed to a shaft 217 supported by roller bearings 218 and 220 along withbushings 218A and 220A, respectively carried in coaxial bores 222 and224 provided through the housing structure 210 and the end cap structure214. The open end of the bore 224 in the end cap 214 is closed by aplate 226 secured thereto by any means such as screws 228.

The periphery of the rotor 216 has a plurality of angularly spaced slots230 as shown in FIG. 6, 'in which are radially slidably carried aplurality of vanes 232,

with the inner ends of the vanes 232 being subjected to fluid pressureintroduced into transverse bores 234 provided at the inner ends of theslots 230.

A fixed cam member 240` is secured in the working chamber 212 andencircles approximately one-half of the rotor 216, The cam member 240has an inner cam surface 242 which is concentric with the rotor outerperiphery and radially outwardly spaced therefrom. A movable cam member244 is disposed in the working chamber 212 and has a portion 246extending oppositely from the fixed cam member 240 and supported forsliding movement in an aperture 248 in the housing structure 210. Themovable cam member 244 has an inner cam surface 250 formed on a radiussubstantially similar to the xed cam member inner surface 242, exceptfor a medial portion to be described, and is adapted for adjustmenttoward and away from the rotor 216 to move the medial portion of theinner cam portion 250 between a zero or minimum expansion position(shown in FIG. 6), wherein the cam surface 250 is substantiallyconcentric to and spaced from the periphery of the rotor 216, and themotor is working at minimum load, to a maximum expansion position,indicated in FIG. l1, where the medial portion of the inner cam surface250 is closely adjacent the rotor periphery, the came surface 250thereby forming adjacent slopes relative to the rotor periphery toprovide adjacent contracting and expanding volumes between successivevanes in the working chamber 212 and to guide the vanes 232 forretraction and extension into and out of the slots 230, the motorworking at maximum load.

The ends of the cam members 240 and 244 have slidable tongue and grooveengagement as seen in the exploded view of FIG. 9, and the ends of thecarne surfaces 242 and 250 are iattened as at 251 to be substantiallytangent to arcs concentric with the rotor 216, and parallel to thedirection of cam member 244 adjustment, so that the vanes 232 will ri-desmoothly from one cam surface to the other as the rotor 215 rotates,regardless of the adjusted position of the movable cam member 244.

The housing 210 and end cap 214 are arranged to provide recesses 252 and254 respectively adjacent portions of the movable cam member 244 on thetwo sides of its medial portion. These recesses 252 and 254 areconnected through respective ports 256 and 258 provided in the housing210 with a source of fluid under pressure (not shown) and a fluidreservoir (not shown). The motor is constructed symmetrically so thateither of the ports 254 or 256 may serve as inlet or outlet ports, foroperation of the rotor 216 in either direction.

For the purpose of the following discussion, the motor will be describedby assuming that fluid under pressure is supplied to the port 256, andthe port 258 is connected with a reservoir. Thus the recess 252 will bedescribed as the inlet recess and the recess 254 will be described asthe outlet recess. Thus, with the movable cam member 244 adjusted towardthe rotor 215, fluid from the inlet recess 252 will move the vanes 232,and consequently rotate the rotor 216 in a counterclockwise direction asseen in FIG. 6, the iiuid moving around the periphery of the rotor 216to be discharged through the outlet recess 254, the volume of workingfluid performing useful work being a function of the proximity of themovable cam member 244 to the rotor 216.

The fixed cam member 240 is provided with an arcuate groove 260 on oneside extending from the end adjacent and open to the inlet recess 252 toa recess 262 open to the working chamber 212 at a location adjacent therotor 216 substantially diametrically opposite the portion of the rotorwhich is exposed to the inlet recess 252. A second arcuate groove 264extends from the end of the fixed cam member 240 adjacent and open tothe end of the outlet recess 254 to a recess 266 opening to the workingchamber 212 at a location adjacent the rotor 216 substantiallydiametrically opposite the portion of the rotor which is exposed to theoutlet recess 254. Admission of the inlet and outlet pressure to thesediametrically opposite portions of the rotor tends to balance the rotoragainst uid pressure forces which would otherwise exert binding and wearproducing stresses on the rotor 216 and its Shaft 217.

It will be seen that as the rotor 216 rotates, the outer ends of thevanes 232 will move between areas of different pressures. Thesepressures need to be balanced at the inner vane ends with substantiallysimilar pressures to prevent the vanes from scoring the cam surfaces orfrom being retracted into their slots. Therefore, arcuate recesses 274and 276 are provided in the housing 210 adjacent the working chamber 212along arcs registering with the bores 234 at the inner ends of vaneslots 230- and in those areas where the outer ends of the vanes 232 aresubjected directly respectively to inlet and outlet pressures. Therecesses 274 and 276 communicate respectively with the recesses 252 and254 by means of passages 278 and 280 respectively provided in thehousing 210.

Other arcuate recesses 282, 284, 286, and 288 are provided in thehousing 210 adjacent the working chamber 212 on arcs registering withbores 234 as the vanes move through areas in which their ends are notsubjected directly to pressures connected with either the inlet or theoutlet. Radial passages 282A, 284A, 286A and 288A connect the respectiverecesses 282, 284, 286, and 2818 with an annular space 290` provided inthe housing at the hub of the rotor 216 around the shaft 217. Thisannular space 290 is provided with uid, under pressure corresponding tothe pressure of the working fluid at the inlet to the motor, through apassage 292 terminating in a port 294 adapted for connection with anysuitable conduit or the like. Introduction of pressure fluid beneath thevanes in these areas will maintain the vanes in contact with the camring members. Additionally, each 'vane is at all time urged outwardly bylightweight springs 296 which are seated in holes extending radiallyinwardly from the bores 234. These bores are axially aligned with theslots 230, and the springs 296 engage in recesses 298 provided in thebases of the vanes 232 as shown in FIG. 10. This will insure that onstarting the motor, and at any time that pressure may be interrupted,the vanes will remain in contact with the cam members. The vanes 232 arebalanced end-to-end by the provision of passages 300 extending from therecess 298 outwardly to the ends of the vanes which are arcuatelygrooved as at 302 so that only the extreme leading and trailing edges ofthe outer ends of the vanes are contacting the cam surfaces and theouter ends of the vanes are therefore subjected to the pressurescommunicated thereto through the passages 300.

The housing 210 has a centrally positioned side recess 304 closed with acover plate 306 secured by screws 308 or the like. An actuator member310 is slidably supported in the recess 304 on a tube 312 extendinginwardly from a uid fitting 314 secured to the housing 210 and the cover306 by any means such as screws 315 as shown in FIG. 6. The tube 312 ishollow for the admission of motor working pressure which is conducted tothe fitting 314 through a conduit (not shown) or the like connected'with the source of working fluid. Pressure admitted through the tube312 to the interior of the actuator 310 tends to move the actuator inthe direction of the arrow shown on the actuator member 310 in FIG. 6,and is opposed by a spring 316 compressed between an abutment plate 317secured to the inner end of the actuator 310 by a screw 317A or the likeand the recess of a closure cap 318 secured to the housing and coverplate 306 by any means such as screws 319.

The outer end surface 320 of the movable cam member portion 246 issloped as shown in FIG. 6 at about a ten degree angle from the normal todirection of movement, and abuts a similarly sloped surface 322 of theactuator member 310, so that as the actuator member 310 is movedlaterally back and forth dependent on variations in pressure admitted toits interior, the movable cam member `will be cammed toward or away fromthe rotor 216. Thus, when the load on the motor is increased tending toslow down the motor, the working pressure will tend to increase, movingthe actuator 310 against the force of the spring 316 to thereby cam themember 244 radially toward the rotor, effecting an increase in theworking force produced by the motor. Conversely, as the load on themotor decreases tending to permit the motor to speed up, the fluidworking pressure will tend to decrease, and the pressure within theactuator 310 will correspondingly decrease so that the spring 316 Willmove the actuator in the opposite direction, and the fluid pressureacting on the interior 'vane-guiding cam surface 250 on the movable cammember 244 Will cause the movable cam member to move away from the rotor216 toward or to the position shown in FIG. 6, effecting a decrease inthe working force produced by the motor. The movable cam member 244 will'be prevented from moving to a fully unloaded position by having theabutment plate 317 adjusted to contact the cam member 244 just prior tothe time it would become completely unloaded, to thereby keep some loadso that the rotor will not overspeed.

It will be seen that the movable cam member 244 is subjected topressures tending to force its end radially outward against the housing,and therefore the cam member portion 246 needs to be balanced againstthese pressures. As seen in FIGS. 6 and 9, recesses 324 and 326 areprovided on the sides of the movable cam member 244 and areinterconnected by a passage 328. When the recess 252 is connected withworking pressure, it is admitted to the passage 328- through a checkvalve 330. When the recess 254 is connected with working pressure, thepressure is admitted to the passage 328 through a similar check valve322 on the other side as shown in FIG. 6. This pressure admitted to bothsides of the movable cam member 244 prevents binding thereof as it movesaxially toward and away from the rotor 216. Further, one side or theother of the extending portion 246 of movable cam member 244 issubjected to working pressure from the recess 252 or 254 (depending onwhich way the motor is working), and to compensate for this unbalancing,a pair of passages 334 and 336 extend from spaces communicatingrespectively with the recesses 252 and 254 to opposite sides of theextending portion 246 to admit the working pressure to respective recess338 or 340 provided on the sides of the aperture 248 in the housing 210.

FIG. 1l is a greatly enlarged view of the previously mentioned medialportion of the movable cam member 44 (or 244) intermediate the inlet andoutlet of the pump or motor, and a corresponding portion of the rotor116 (or 216), illustrating the cam surface 50 (or 250) in a normaloperating position (solid-line A) about half-way between the minimumexpansion position (dash-line B) and the maximum expansion position(dash-line C), the enlargement illustrating an important feature of theinvention. In the solid-line position shown, the actual contour of themedial portion between points X and Y is on a radius concentric with theperipheral surface of the rotor 16 (or 216), so that in normal operationthere will be no sudden transition between contraction and expansion ofthe fluid chamber which I have found will otherwise tend to producedisruptive surges in fluid pressures. The remainder of the cam surface50 (or 250) beyond the points X and Y is radiused similarly to theradius of the fixed cam member 40 (or 240) so that the ends of the camsalways meet. The dot-dash lines D, E and F indicated in FIG. 1lillustrate how the medial portion between points X and Y would appearrespectively at the normal, minimum expansion, and maximum expansionpositions if the cam surface 50 (or 250) medial portion were radiusedlike the rest of the surface beyond the points X and Y. Thus it isapparent that this slight deviation from constant radius in the medialportion will have little effect at either the minimum or maximumpositions, yet in or near normal operating position the surge-freefunction will be effective.

Although I have described and shown only one modification of myinvention, it Will be apparent to one skilled in the art that variouschanges and modifications may be made therein without departing from thespirit of the invention or the scope of the appended claims.

What is claimed is:

1. A variable capacity mechanism for expansible chamber fluid pumps andmotors comprising:

(a) a housing having a fluid chamber,

(b) a rotor in said chamber and angularly spaced radially slidable vanescarried by said rotor,

(c) cam means contacting and guiding said vanes for sliding operation assaid rotor turns, said cam means having:

(l) a fixed cam member having an inner surface substantially concentricto and outwardly spaced from approximately one-half of said rotor,

(2) a movable cam member having an inner surface radius substantiallysimilar to the fixed member inner surface radius and movable between aminimum expansion position substantially concentric to and outwardlyspaced from the other approximately one-half of said rotor and a maximumexpansion position in which the mid-section of the movable cam memberinner surface is disposed closely adjacent the rotor,

(d) an inlet to said chamber adjacent said other onehalf of said rotorat one side of said midsection of the movable cam member,

(e) an outlet connected to said chamber adjacent said other one-half ofsaid rotor at the other side of said midsection of the movable cammember, and

(f) the separation between said inlet and outlet being greater than thespacing between any two successive vanes.

2. The mechanism as dened in claim 1 and in which the ends of said cammembers have slidable tongue and groove engagement and in which theinner surfaces of the cam member ends are approximately tangent to arcsconcentric to the rotor and extend parallel with the direction ofmovement of said movable cam member.

3. The mechanism as defined in claim 1 and in which:

(a) said housing has an aperture extending radially outward from saidfluid chamber on the side opposite said fixed cam member,

(b) said movable cam member has a portion carried by and radiallyslidable in said aperture, and

(c) said housing carries means operatively connected with the movablecam member and adjusting same radially toward and away from said rotorresponsive to fluid pressure.

4. The mechanism as defined in claim 3 and in which said last-mentionedmeans comprises an actuator having a camming surface slidably coactingwith a cammed surface on said movable cam member, and pressureresponsive means operable to adjust said actuator relative to saidmovable cam member for camming same toward and /away from said rotor.

5. The mechanism as defined in claim 3 and in which:

(a) said movable cam member slidably carried portion has a cammedsurface on the side opposite the inner surface which contacts said vanesand sloped at an angle to a plane extending normal to the movable camdirection of movement,

(b) an actuator having a camming surface slidably coacting with saidmovable cam member cammed surface, and

(c) pressure responsive means operable to adjust said actuator relativeto said movable cam member for camming .same toward and away from saidrotor.

6. The mechanism as defined in claim 3 and in which:

(a) said movable cam member slidably carried portion has a cammedsurface on the side opposite the inner surface which contacts said vanesand sloped at an angle of about ten degrees to a plane extending normalto the movable cam direction of movement,

(b) an actuator having a camming surface slidably coacting andcomplementary with said movable cam member cammed surface, and

(c) pressure responsive means operable to adjust said actuator relativeto said movable cam member for camming same toward and away from saidrotor.

7. The mechanism as defined in claim 5 when used in a pump and in which:

(a) said actuator has means resiliently urging same toward a directioncamming the movable cam member toward said rotor for increasing pumpdelivery,

(b) means opposing said resilient urging means with a pressureproportional to tendencies of said pump to increase delivery pressure,and

(c) said movable cam portion is urged radially outwardly from said rotorby pump pressure directed against said inner cam surface.

8. The mechanism as defined in claim 5 when used in a motor and inwhich:

(a) said actuator has means resiliently urging sarne toward a directionpermitting the movable cam member to move away from said rotor fordecreasing the motor working force,

(b) means opposing said resilient urging means with a pressureproportional to motor inlet pressure as determined by the load on saidmotor, and

(c) said movable cam portion is urged radially outwardly from said rotorby working pressure directed against said inner cam surface.

9. A variable capacity mechanism for expansible chamber fluid pumps andmotors comprising:

(a) a housing having a fluid chamber,

(b) a rotor in said chamber and angularly spaced radially slidable vanescarried by said rotor,

(c) cam means contacting and guiding said vanes for sliding operation assaid rotor turns, said cam means having:

(l) a fixed cam member having an inner surface substantially concentricto and outwardly spaced from approximately one-half of said rotor,

(2) a movable cam member having an inner surface radius substantiallysimilar to the fixed member inner surface radius and movable between aminimum expansion position substantially concentric to and outwardlyspaced from the other approximately one-half of said rotor and a maximumexpansion position in which the midsection of the movable cam memberinner surface is disposed closely adjacent the rotor,

(d) an inlet to said chamber adjacent said other onehalf of said rotorat one side of said midsection of the movable cam member,

(e) an outlet connected to said chamber adjacent said other one-half ofsaid rotor at the other side of said midsection of the movable cammember, and

(f) means connecting said inlet and outlet with said fluid chamberdiametrically opposite respectively said inlet and outlet to tend tobalance pressures radially directed on said rotor.

10. A variable capacity mechanism for expansible chamber fluid pumps andmotors comprising:

(a) a housing having a fluid chamber,

(b) a rotor in said chamber and angularly spaced radially slidable vanescarried by said rotor,

(c) cam means contacting and guiding said vanes for sliding operation assaid rotor turns, said cam means having:

(l) a fixed cam member having an inner surface substantially concentricto and outwardly spaced from approximately one-half of said rotor,

(2) a movable cam member having an inner surface radius substantiallysimilar to the fixed member inner surface radius and movable between aminimum expansion position substantially concentric to and outwardlyspaced from the other approximately one-half of said rotor and a maximumexpansion position in which the midsection of the movable cam memberinner surface is disposed closely adjacent the rotor,

(d) an inlet to said chamber adjacent said other onehalf of said rotorat one side of said midsection of the movable cam member,

(e) an outlet connected to said chamber adjacent said other one-half ofsaid rotor at the other side of said midsection of the movable cammember, and

(f) said rotor having angularly spaced slots in its periphery carryingsaid vanes for radial extension and retraction thereof as guided by saidcam means,

(g) means connecting the inner ends of said vanes to inlet and outletpressures varying to effect balancing of said vanes as they move intoareas of diierent pressures,

(h) said vanes having means restrictingly connecting the inner ends tothe outer leading side ends, and

(i) means connecting the inner vane ends to pressure restrictedproportionately with the aforesaid restrictingly connecting means assaid vanes move from outlet-connected to inlet-connected areas of saidchamber whereby to provide gradual changes in balancing pressures.

11. The mechanism as dened in claim 1 and including means pressurebalancing said movable cam member normally with respect to the directionof cam member movement and to the axis of said rotor.

12. A variable capacity mechanism for expansible chamber uid pumps andmotors comprising:

(2) a movable cam member having an inner surface radius substantiallysimilar to the xed member inner surface radius and movable between aminimum expansion position substantially concentric to and outwardlyspaced from the other approximately one-half of said rotor and a maximumexpansion position in which the midsection of the movable cam memberinner surface is disposed closely adjacent the rotor,

(d) an inlet to said chamber adjacent said other onehalf of said rotorat one side of said midsection of the movable cam member,

(e) an outlet connected to said chamber adjacent said other one-half ofsaid rotor at the other side of said midsection of the movable cammember, and

(f) said movable cam member inner surface having a medial portionextending between the inlet and outlet and radiused to be concentricwith the rotor periphery only when the movable cam member is positionedabout midway between its minimum and maximum expansion positions, theremainder of said movable cam member inner surface being substantiallyconcentric with the rotor periphery only when the movable cam member ispositioned at its minimum expansion position.

References Cited UNITED STATES PATENTS 1,693,540 11/1928 c Balsiger.2,170,786 8/ 1939 McElroy et al. 2,238,786 4/ 1941 Warman. 3,117,528l/1964 Rosaen. 3,272,139 9/1966 Rosaen.

FOREIGN PATENTS 502,418 4/ 1951 Belgium. 415,472 6/ 1925 Germany.

DONLEY J. STOCKING, Primary Examiner WILBUR I. GOODLIN, AssistantExaminer U.S. C1. X.R.

(El/69) UNITED STATES PATENT oFFICE CERTIFICATE OF CORRECTION Parent No.Y 3,456,593 Dated July-22, '1969 Inventor(s) Oscar E. Rosaen It iscertified tha and that said Letters Pa t error appears in theaboveidentified patent tent are hereby corrected as shown below:

IN TI-IE SPECIFICATIONS Column 6, line 25, change "came" to cam.

Column 6, line 33, change "came" to "Cal--o SIGNED AND SEALED m12819706m) Attest:

Edward M. Fletcher, Ir.

WILLIAM E. Sm, IR. P tents Atting Officer Gomssioner of a

